Non-imaging electro-optic vehicle sensor apparatus utilizing variance in reflectance

Apparatus for monitoring vehicle highway usage and for providing information indicative of the passage of a vehicle over the highway, the type of vehicle, and the vehicle's speed, comprising:

• a light source providing light having a predetermined set of light characteristics;
• means for mounting said light source above the highway with said light source directing its lumination downwardly onto the highway with incident light from said light source being reflected off a surface of the highway;
• first detector means, a second detector means, and a third detector means for detecting reflected light from said light source, the reflected light from said surface having light characteristics which vary in response to passage of a vehicle over the highway and through respective first and second paths of light which are created between said light source and the respective detector means;
• and,
• processor means processing reflected light detected by each of said detector means and variations in the light characteristics thereof caused by passage of a vehicle, said processor means processing said detected light to determine passage of a vehicle, the vehicle type, and the vehicle's speed, and vehicle acceleration to enable a traffic controller to determine highway usage at any given time and control traffic flow of vehicles over the highway.

A method of monitoring vehicle usage on a multi-lane roadway comprising:

• mounting at least one light source above each lane of the roadway and emitting light from the light source such that the light is directed downwardly onto the roadway with incident light from the light source being reflected off a surface of the roadway;
• detecting through at least one optical detector for each lane, emitted light from the light source associated with each lane reflected off the roadway surface and ambient light on the roadway surface including light from vehicle headlights, each optical detector and the light from each associated light source directed at the roadway surface defining a footprint on the roadway surface over which vehicles pass, the reflected light having an AC ripple, whose amplitude is a function of an AC power source for the light, said amplitude varying in response to reflection of the light from the roadway surface and the passage of a vehicle over the defined footprint and through a path of light between the light source and the optical detector;
• adjusting a threshold of light detection in accordance with changes in the ambient light conditions and the change from day to night and vice versa;
• filtering the detected light to filter out light of a wavelength other than that from each light source;
• amplifying said filtered light to produce an analog output signal;
• converting said analog output signal to a digital signal;
• and
• processing the digital signal to detect variations in the amplitude of the AC ripple caused by the passage of a vehicle to determine the number, speed, and type of vehicles passing over each lane of the roadway during a predetermined period of time, regardless of the lane in which the vehicles travel.

A method for detecting vehicle usage passage over a road and for determining the type of vehicle and the vehicle's speed comprising:

• providing an AC light source;
• powering said light source from an AC power source;
• mounting said light source above the road for light from said light source to be directed downwardly onto a road surface with incident light from said source being reflected off the surface, incident light from said light source including an AC ripple whose frequency is a function of the AC power source;
• detecting light from said light source using a first detector means, a second detector means, and a third detector means, the amplitude of the AC ripple in the light reflected from the road varying in response to passage of a vehicle over the road and through respective paths of light created between said light source and each of the respective detector means;
• and,
• processing said detected light using processor means processing the reflected light detected by each from each of said detector means and variations in the amplitude of the AC ripple caused by passage of a vehicle, said processing of said detected light providing information used to determine passage of a vehicle, the vehicle's type, and the vehicle's speed and acceleration.

In a multi-lane highway over which different types of vehicles travel, the volume of vehicles traveling over the highway differing at different times of the day and night, and the speed and acceleration of the vehicles also differing, a method for determining the vehicle usage at any one time for a highway controller to control traffic flow of vehicles over the highway comprising:

• installing an AC light source over each lane of the highway;
• supplying AC power to the light sources to power the lights;
• mounting respective first and second light detector means with each said light source;
• linearly spacing the respective detector means apart from their associated light source along a longitudinal centerline of the lane;
• directing light from each light source downwardly onto a surface of the highway with incident light from each source being reflected off the highway surface, the incident light from each light source including an AC ripple whose frequency is a function of the AC power source;
• detecting the reflected light from each light source using said first and second light detector means, the amplitude of the AC ripple in the reflected light varying in response to passage of a vehicle over the highway and through respective first and second non-convergent paths of light created by a light source and said detector means;
• adjusting a threshold of light detection of the detector means as a function of changes in ambient light conditions and the transition from day to night and vice versa;
• and,
• processing the reflected light detected from the respective detector means and variations in the AC ripple therein caused by passage of a vehicle, processing of the detected light by the processor means being used to determine passage of the vehicle, the vehicle type, and the vehicle's speed thereby to enable a traffic controller to control traffic flow.